Bag packaging method

ABSTRACT

A bag packaging method by which a mouth portion of a thin plastic-made bag filled with articles can be sealed without creases is provided. A bag  4  filled with sliced bread  1  is conveyed by a blade conveyor  6 . A mouth portion of the bag  4  is led between upper and lower two conveyor belts  20, 21 . While a suction force acting on upper and lower sides of the mouth portion is applied from vacuum chambers  23, 24  through the conveyor belts  20, 21 , air is blown from a sirocco fan  13  toward a mouth of the bag  4  so that the mouth portion of the bag  4  is opened. Two mouth spreader bars  30  having an interval between their distal ends narrowed are inserted into the bag  4  so opened. Then, the mouth spreader bars  30  have the interval widened to thereby spread the mouth portion flat. The mouth portion of the bag  4  spread flat is pinched and sealed by a sealer  50  without generation of creases.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a bag packaging method for producing a bag package of articles by sealing a mouth portion of a thin soft plastic bag filled with articles.

2. Description of the Prior Art

A bag packaging method for producing a bag package by filling articles in a plastic-made bag and then sealing a mouth portion of the bag is widely practiced. However, while such a bag packaging method is carried out for packaging using a thick and comparatively strong plastic bag, under the present circumstances, such method is not practically used for packaging using a thin soft plastic bag. The reason therefor is that once the thin soft plastic bag is filled with articles, even if the mouth portion thereof is wanted to be sealed, the bag is very soft and weak so that it is extremely difficult to seal the mouth portion without generation of creases.

For example, in a marketed package using a thin plastic bag filled with sliced bread, buns, cookies or the like, the bag mouth portion is not sealed but, in many cases, the mouth portion is only bound being fitted with a plastic-made clip or being simply wound with a tape or cord. Thus, as the mouth portion of the bag package using the thin plastic bag is not tightly closed by sealing, there is a problem that sweet smells come out of the bread or the like in the bag so that small insects are induced to enter the bag or dusts may come into the bag in the course of distribution. Especially, while such small insects or dusts stick to the mouth portion of the bag, if the clip or tape binding the mouth portion is detached, there is a large possibility that the insects or dusts come into the bag.

In order to avoid the above-mentioned problem, when the sliced bread or the like is put into the thin plastic bag, the mouth portion thereof is preferable to be sealed. However, the mouth portion of the bag is too weak to keep standing or, even if it is laid down, it is hardly spread flat without generation of creases. Hence, sealing of the mouth portion is difficult. Even if the sealing is done, creases are generated so that commercial value of the packaged articles will be largely reduced. Recently, there is seen in the market such a bag package as is so made that the mouth portion of the thin plastic bag filled with sliced bread or the like is once sealed and then bound by tape or cord. However, in such sealing of the mouth portion, there are seen many shortcomings such that many creases are generated in the sealed portion of the bag mouth portion and heating for the sealing is not uniformly done because of the creases of the sealed portion so that the sealed portion may partially melt to be broken or the mouth portion may open because of the insufficient sealing.

SUMMARY OF THE INVENTION

In view of the problems in the prior art, it is an object of the present invention to provide a bag packaging method by which a mouth portion of a thin plastic bag filled with articles to be packaged can be beautifully, securely and stably sealed without generation of creases.

In order to achieve the above-mentioned object, the present invention provides a bag packaging method comprising the steps of: while causing a suction force to act on both sides, opposed to each other, of a mouth portion of a bag filled with articles, opening the mouth portion of the bag by blowing air toward a mouth of the bag, inserting two mouth spreader bars having an interval between their distal ends narrowed into the bag so opened, causing the mouth spreader bars to have the interval laterally widened to thereby spread the mouth portion of the bag flat, and causing a sealer to pinch and seal the mouth portion of the bag so laterally spread.

While the air blowing toward the mouth of the bag according to the present invention may be continuously carried out, if the suction force is kept acting on the both sides of the mouth portion of the bag, the air blowing may be done only for a short time as a trigger to initiate the bag opening so that a later action to make the opening larger is carried out by the suction force acting from the both sides.

According to the bag packaging method of the present invention, while the suction force is caused to act on the both sides, opposed to each other, of the mouth portion of the bag filled with articles, air is blown toward the mouth of the bag so that the mouth portion of the bag is opened by the air blowing. Thus, by the air easily entering the bag as well as by the suction force acting on the both sides, opposed to each other, of the mouth portion of the bag, the bag can be smoothly, securely and largely opened.

Then, the two mouth spreader bars are inserted into the mouth portion of the bag so opened and the mouth portion of the bag filled with articles is laterally (horizontally) spread flat.

In this way, the mouth portion of the bag so spread flat is pinched and sealed by the sealer. Hence, the mouth portion of the bag can be sealed without generation of creases.

In the bag packaging method according to the present invention, the step of causing the suction force to act on the both sides of the bag may be carried out by leading the mouth portion of the bag between upper and lower two conveyor belts, each comprising an air suction means, arranged to run in a running direction of the bag with an interval maintained between the two conveyor belts. Thereby, the suction force acts on the mouth portion of the bag from both of upper and lower sides thereof and the bag can be quickly opened.

In such construction that the mouth portion of the bag is led between the two conveyor belts, each comprising the air suction means, arranged with the interval maintained between the two conveyor belts so that the suction force acts on the mouth portion of the bag from both of upper and lower sides thereof, the two conveyor belts may be arranged such that the interval between the two conveyor belts is gradually increased toward the running direction of the bag. Thereby, the mouth portion of the bag to be opened by action of the suction force is gradually opened larger and the bag can be securely opened.

Also, in the bag packaging method according to the present invention, the steps may include causing an air squeezer to push the mouth portion of the bag, moving the bag relative to the air squeezer to thereby cause the air squeezer to squeeze air existing between the mouth of the bag and the articles filled in the bag to be discharged outside, and then carrying out the sealing of the mouth portion of the bag. By so doing, there remains no surplus air in the bag so sealed, which is preferable.

In this case, the movement of the bag relative to the air squeezer may be done by retraction of the mouth spreader bars having the interval laterally widened from the mouth portion of the bag as well as by pushing out a bottom portion of the bag. By so doing, there is needed no complicated structural members for moving the bag relative to the air squeezer and the air discharge from the bag can be securely carried out.

Furthermore, in the bag packaging method according to the present invention, the steps may include inserting an air suction pipe together with the two mouth spreader bars into the bag having the mouth so opened, causing the air suction pipe to suck out air in the bag having the mouth portion so spread flat by the mouth spreader bars to be discharged outside, and then carrying out the sealing of the mouth portion of the bag having the air so discharged outside. By so doing, the air in the bag can be securely discharged outside and the articles filled in the bag can be maintained fresh for a longer time.

In this way, according to the bag packaging method of the present invention, even if the bag is made of a very thin and weak plastic film, the mouth of the bag can be securely opened and by the mouth spreader bars inserted thereinto, the mouth portion of the bag is spread flat and can be securely and quickly sealed without generation of creases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory plan view showing a construction of a bag packaging apparatus in which the bag packaging method of the present invention is applied to packaging of sliced bread.

FIG. 2 is a cross sectional view taken on line A-A of FIG. 1.

FIG. 3 is a cross sectional view taken on line B-B of FIG. 1.

FIG. 4 is an explanatory view showing various states of two conveyor belts having air suction holes seen in the direction of arrow C of FIG. 1, wherein the states where a mouth portion of a bag is led between the two conveyor belts and largely opened so that two mouth spreader bars are inserted thereinto are shown in the order of states (a) to (d).

FIG. 5 is an explanatory view showing a construction and function of the mouth spreader bars used at position of arrow C of the apparatus of FIG. 1, wherein (a) shows a state that the mouth spreader bars spread the mouth portion of the bag and (b) shows a state that the mouth spreader bars have an interval between them narrowed.

FIG. 6 is an explanatory view of widening and narrowing actions of the mouth spreader bars in the order of state (a) to state (e).

FIG. 7 is an explanatory view of a construction and function, in the order of state (a) to state (d), of a pusher bar arranged being opposed to the mouth spreader bars at position of arrow C of the apparatus of FIG. 1.

FIG. 8 is a cross sectional view taken on line D-D of FIG. 1.

FIG. 9 is an explanatory view showing a modified construction of the two conveyor belts having air suction holes shown in FIG. 4.

FIG. 10 is a side view showing another example of a carrier belt conveying the mouth portion of the bag.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Herebelow, the present invention will be concretely described based on embodiments, as illustrated, in which the bag packaging method according to the present invention is applied to packaging of sliced bread using a thin plastic bag.

Embodiment 1

FIG. 1 is an explanatory plan view showing an entire construction example of a bag packaging apparatus in which the bag packaging method of the present invention is applied to packaging of sliced bread. There, numeral 2 designates a feed conveyor by which a bag 4 from the previous filling step, filled with sliced bread 1 and having its mouth portion to be sealed, is conveyed in the direction of arrow 3, wherein the mouth portion is directed toward the upstream side. Numeral 6 designates a blade conveyor receiving the bag 4 filled with the sliced bread 1 that has been conveyed by the feed conveyor 2 to be further conveyed in the direction of arrow 5, wherein the bag 4 has the mouth portion transversely directed relative to the direction of arrow 5, the direction of arrow 5 being orthogonal to the direction of arrow 3.

Numeral 7 designates a guide. When a bottom portion of the bag 4 having the sliced bread 1 conveyed by the feed conveyor 2 abuts on the guide 7, as shown in FIG. 2, the guide 7 functions to guide the bag 4 having the sliced bread 1 to be conveyed by the blade conveyor 6. Numerals 10 and 11 designate endless belt conveyors, arranged in parallel to each other, on which the mouth portion of the bag 4 is placed to be conveyed at the same velocity as the portion of the bag 4 where the sliced bread 1 is filled.

The belt conveyors 10, 11 are made of a material having an adhesive nature relative to the plastic-made bag so that the thin plastic bag is kept adhering, for which silicone belts, urethane belts or the like can be named. The belt conveyors 10, 11 are provided extending in parallel to each other with an interval maintained between them so as to run in the direction of arrows 12. A position relation of the feed conveyor 2, blade conveyor 6, guide 7 and bag 4 having the sliced bread 1 at a cross sectional position along line A-A of FIG. 1 is shown in a cross sectional side view of FIG. 2.

In FIG. 1, numeral 13 designates a sirocco fan arranged along the conveying path of the bag 4 having the sliced bread. While the bag 4 having a bottom face of the mouth portion placed on the belt conveyors 10, 11 is being conveyed, when the mouth of the bag 4 comes to the position in front of the sirocco fan 13, air is blown from the sirocco fan 13 toward the mouth of the bag 4, as shown in FIG. 3, to thereby cause the air to easily enter the bag 4 as a trigger to open the mouth portion of the bag 4 by a suction force acting on the mouth portion of the bag 4, as will be described later. In FIG. 3, numeral 14 designates an air cylinder that moves an air shutter 15 so that the air from the sirocco fan 13 is blown toward the mouth of the bag 4 or the air blowing is shut off.

As shown by broken lines in FIG. 1, toward downstream from the position where the sirocco fan 13 is arranged, endless conveyor belts 20, 21 are provided, wherein the conveyor belt 20 is arranged above the conveyor belt 21 with an interval being maintained between them, as shown in FIG. 3, so that the mouth portion of the bag 4 is led into this interval. Each of the conveyor belts 20, 21 is constructed by a porous belt having a multiplicity of small holes of appropriate sizes so as to be permeable.

A position relation between the conveyor belts 20, 21 and the belt conveyors 10, 11 is appropriately set, for example, such that the conveyor belts 20, 21 are arranged between the belt conveyors 10 and 11 or one or both of the belt conveyors 10, 11 have their lengthwise central portions cut off so that upstream portions and downstream portions are formed and the conveyor belts 20, 21 are arranged between the upstream portions and downstream portions.

As somewhat exaggeratedly shown in FIG. 3 as well as in FIG. 4 that is a view of the conveyor belts 20, 21 seen in the direction of arrow C in FIG. 1, vacuum chambers 23, 24 are provided within loops formed by the conveyor belts 20, 21, respectively. In a bottom face member of the vacuum chamber 23 opposed to the vacuum chamber 24 as well as in an upper face member of the vacuum chamber 24 opposed to the vacuum chamber 23, a multiplicity of air suction holes are provided. When the mouth portion of the bag 4 is led into the interval between the conveyor belts 20 and 21, suction forces from the vacuum chambers 23, 24 act on the mouth portion of the bag 4 through the conveyor belts 20, 21 constructed by the porous belts so that the suction forces want to separate from each other the upper and lower plastic sheets forming the mouth portion of the bag 4.

As the sirocco fan 13 is arranged at the position of the conveyor belts 20, 21, as mentioned above, when the mouth portion of the bag 4 is led into the interval between the conveyor belts 20 and 21, air is blown toward the mouth of the bag 4 from an air blowing port 18 of the sirocco fan 13. By this air blowing, a small opening of the mouth of the bag 4 is formed as a trigger of the bag opening. Thus, when the suction forces from the vacuum chambers 23, 24 act through the conveyor belts 20, 21, air easily enters the bag 4 so that the bag opening can be easily and securely carried out.

As the air from the sirocco fan 13 is needed only for forming the small opening of the mouth of the bag 4 as the trigger of the bag opening, the air blowing toward the mouth of the bag 4 that is being conveyed is also needed only for a short time while the bag 4 is nearby passing. For this purpose, the air cylinder 14 moves the air shutter 15 so that the air from the sirocco fan 13 is blown or the air blowing is shut off.

In this way, as shown by the sequence of states (a) to (d) of FIG. 4, the mouth portion, shown by reference numeral 25 in FIG. 4, etc., of the bag 4 that is being conveyed is largely opened to the size of the interval between the conveyor belts 20 and 21 by the suction forces acting from the vacuum chambers 23, 24 through the conveyor belts 20, 21.

At position of arrow C in FIG. 1 to which the bag 4 having the mouth portion 25 opened by the air blowing and air sucking is being conveyed, mouth spreader bars 30 are arranged. The mouth spreader bars 30 function to spread flat the mouth portion 25 of the bag 4 so opened and the construction thereof will be described with reference to FIGS. 5 and 6.

The mouth spreader bars 30 comprise a pair of bars 30. In FIG. 5 showing details thereof, the respective mouth spreader bars 30 are pivotably arranged around a pivotal center 31, as shown by arrow 32, and a spring 33 is provided at position below the pivotal center 31 so that the respective mouth spreader bars 30 are pulled toward each other. The mouth spreader bars 30 have their proximal ends fitted with cam followers 34 and when the mouth spreader bars 30 are advanced in the direction of arrow 35 and retracted in the direction of arrow 36, the cam followers 34 are moved along cam faces, as will be described later.

In FIG. 5, numeral 38 designates an air cylinder that moves a piston bar 39 forward and backward. The piston bar 39 has its distal end fitted with a lateral bar 40. The lateral bar 40 has its both end portions pivotably connected to the pivotal centers 31 of the mouth spreader bars 30. C1 designates advance cams along which the cam followers 34 are guided when the mouth spreader bars 30 are advanced in the direction of arrow 35. C2 designates a retraction cam along which the cam followers 34 are guided when the mouth spreader bars 30 are retracted in the direction of arrow 36.

The retraction cam C2 is formed by a rectangular plate and the cam followers 34 are guided along both side faces of the retraction cam C2. Each of the advance cams C1 is constructed by two portions, one being a cam portion 44 that does not move being fixed to a machine frame or the like, the other being a cam portion 45 that is pivotably provided around a pin 46 provided at a rear end of the cam portion 44. The cam portion 45 is pulled toward the air cylinder 38 by a spring 47 to be so urged that an end of the cam portion 45 on the opposite side of the pivotal center of the pin 46 abuts on a side face of the retraction cam C2.

Next, function of the mouth spreader bars 30 narrowed and widened by the cams C1, C2 will be described with reference to FIG. 6.

In state (a) of FIG. 6, the piston bar 39 is retracted by the air cylinder 38 so that the mouth spreader bars 30 are on a retracted position, the cam followers 34 of the mouth spreader bars 30 abut on the side faces of the retraction cam C2 and the mouth spreader bars 30 have an interval between them widened. In state (b) of FIG. 6, the piston bar 39 is slightly elongated from the state (a) so that the cam followers 34 begin to ride on the cam portions 45 of the advance cams C1 from the side faces of the retraction cam C2 and the mouth spreader bars 30 begin to be narrowed. As the piston bar 39 is further elongated and the cam followers 34 are moved on the cam portions 45, an interval between distal ends of the mouth spreader bars 30 is narrowed corresponding to the position on inclination of the cam portions 45. When the cam followers 34 are moved onto the cam portions 44, arranged in parallel to each other, from the cam portions 45, the interval between the distal ends of the mouth spreader bars 30 is further narrowed, as shown in state (c) of FIG. 6. The mouth spreader bars 30 having their distal ends so narrowed are advanced in the direction of arrow 35 to be inserted into the mouth portion of the bag 4 that is opened by the air blowing and air sucking, as mentioned above.

The piston bar 39 is further elongated and the cam followers 34 are moved onto the mutually parallel cam portions 44 from the cam portions 45. Then, by the piston bar 39 further elongating, the cam followers 34 are disengaged from the advance cams C1 and abut on the side faces of the retraction cam C2 so that the distal ends of the mouth spreader bars 30 are kept widened by the cam C2 and spring 33, as shown by state (d) of FIG. 6. Thereby, the mouth portion of the bag 4 is laterally (horizontally) spread flat. Then, as shown by state (e) of FIG. 6, the piston bar 39 is retracted in the direction of arrow 36 and the mouth spreader bars 30 kept widened by the cam followers 34 abutting on the side faces of the retraction cam C2 are also retracted. Thus, the mouth spreader bars 30 are returned to the state (a) of FIG. 6. By these movements, the mouth portion of the bag 4 is laterally spread to be formed flat. Thereafter, the same actions are repeated.

When the cam followers 34 abutting on the side faces of the retraction cam C2 are to be retracted, the cam portions 45 of the advance cams C1 are rotationally lifted around the pin 46 against an activating force of the spring 47, as shown by broken lines of the state (e) of FIG. 6, and thus the cam followers 34 keeping abutting on the side faces of the retraction cam C2 can be retracted without being influenced by the cam portions 45.

In this way, the cam followers 34 engage with different cams between the advancing time and retracting time and thereby both of the narrowing action of the mouth spreader bars 30 to be inserted into the bag and the widening action of the mouth spreader bars 30 necessary for laterally spreading the mouth portion of the bag can be quickly carried out.

As described above, by being moved forward and backward (in the directions of arrows 35, 36) relative to the mouth of the bag 4 having the sliced bread, the respective mouth spreader bars 30 are displaced, as shown by arrow 32, so that the interval between the two mouth spreader bars 30 is narrowed and widened. The mouth spreader bars 30 having the interval between their distal ends narrowed, as shown by (b) of FIG. 5 or (c) of FIG. 6, are inserted into the bag 4 having the mouth portion opened by the air sucking from above and from below, as shown in FIG. 4. Then, the cam followers 34 engage with the side faces of the retraction cam C2 so that the mouth spreader bars 30 have the interval of their distal ends widened, as shown by (a) of FIG. 5 or (d) of FIG. 6, and the mouth portion of the bag 4 is laterally spread. In this state, the mouth spreader bars 30 are retracted in the direction of arrow 36 to be drawn out of the bag 4.

In FIGS. 1 and 5(a), numeral 41 designates an air squeezer provided to be moved up and down. When the air squeezer 41 is moved down, it slightly pushes down the mouth portion of the bag 4 that has been spread flat by the mouth spreader bars 30. While the air squeezer 41 is moved down, when the mouth spreader bars 30 having their distal ends widened, as shown in (a) of FIG. 5, is retracted in the direction of arrow 36 to be drawn out of the bag 4, the bag 4 having the sliced bread is pulled to be moved in the direction of arrow 42. By this movement of the bag 4, air in a non-filled space 43 of the bag 4 is squeezed to be discharged outside by the air squeezer 41 that is stopped at that time.

On the other hand, at position of arrow C of FIG. 1 opposed to the mouth spreader bars 30, an air cylinder 48 comprising a pusher bar 49 is provided. When the pusher bar 49 is pushed out by the air cylinder 48, a bottom of the bag 4 having the sliced bread is pushed out toward the mouth spreader bars 30. Operation of the pusher bar 49 to push the bottom of the bag 4 in the direction of arrow 42 is synchronized with the action of the mouth spreader bars 30 to pull the bag 4 in the direction of arrow 36, as described with respect to FIG. 5, so that the above-mentioned action to squeeze the air in the bag 4 by the air squeezer 41 is assisted.

The air squeezing action of the air in the bag 4 by the mouth spreader bars 30, air squeezer 41 and pusher bar 49 is shown in FIG. 7. In state (a) of FIG. 7, the mouth spreader bars 30 having their distal ends narrowed are being inserted into the bag 4 having the mouth portion opened by action of the suction forces through the conveyor belts 20, 21. In state (b) of FIG. 7, the mouth spreader bars 30 inserted into the mouth portion of the bag 4 have their distal ends widened. In state (c) of FIG. 7, the mouth spreader bars 30 having their distal ends fully widened in the mouth portion of the bag 4 are being retracted. As the mouth spreader bars 30 having their distal ends widened are retracted, the bag 4 is pulled and, at the same time, the bottom of the bag 4 having the sliced bread is pushed toward the mouth spreader bars 30 by the pusher bar 49 pushed out by the air cylinder 48. By these movements, the air in the bag 4 is squeezed by the air squeezer 41 to be discharged out of the mouth portion of the bag 4.

In state (d) of FIG. 7, the air discharge from the bag 4 is completed, the air cylinder 48 is retracted and the mouth spreader bars 30 are about to be drawn out of the bag 4.

The bag 4 having the mouth portion spread flat as described with respect to FIGS. 6 and 7 is further conveyed and the mouth portion of the bag 4 is sealed. In FIG. 1, numeral 50 designates a sealer comprising an air cylinder 51 moving the sealer 50 up and down and sealer receiver 52, as shown in FIG. 8. Numeral 53 designates an endless belt provided above the belt conveyor 11 so as to be moved at the same velocity and in the same direction as the belt conveyor 11. The mouth portion of the bag 4 spread flat on the belt conveyors 10, 11 by the mouth spreader bars 30 is pinched between the endless belt 53 and belt conveyor 11 and, while maintained flat, is sealed by the sealer 50.

Sealing of the mouth portion of the bag 4 is carried out while the bag 4 placed on the belt conveyors 10, 11 is being conveyed. Hence, the sealer 50 and sealer receiver 52, while effecting the sealing action of the mouth portion of the bag 4 pinched between the sealer 50 and sealer receiver 52, move at the same velocity as the bag 4 and, upon completing the sealing, loosen the pinching of the bag 4 and quickly return to the original position. These movements are repeated. This type of sealer is generally known. As an appropriate sealer of known construction can be used for practicing the present invention, description thereof will be omitted. In FIG. 1, numeral 60 designates a sealed portion of the bag 4 and numeral 70 a binder. The binder 70 functions to fold and bind the sealed portion of the bag 4 having the mouth portion sealed, as mentioned above. As the binder 70, an appropriate binder of known construction can be used for practicing the present invention, description thereof will be omitted.

According to the bag packaging apparatus of the construction as illustrated, the bag 4 filled with the sliced bread is sealed to be packaged, as follows. That is, as shown in FIG. 1, when the bag 4 having therein the sliced bread 1 is conveyed by the blade conveyor 6 and belt conveyors 10, 11 and comes to the position where the conveyor belts 20, 21 are arranged, the mouth portion of the bag 4 receives the suction forces from the vacuum chambers 23, 24 through the upper and lower conveyor belts 20, 21 arranged with an interval maintained between them. In this state, air blowing is effected from the sirocco fan 13 toward the mouth of the bag 4. Thereby, the mouth portion of the bag 4 is opened so that the mouth portion of the bag 4 is drawn upward and downward by the suction forces acting from the vacuum chambers 23, 24. That is, upper and lower two film sheets forming the mouth portion 25 of the bag 4 are drawn upward and downward to stick to the conveyor belts 20, 21 and the mouth portion 25 of the bag 4 is largely opened, as shown in state (c) of FIG. 4.

The air blowing from the sirocco fan 13 is sufficient if it slightly opens the mouth of the bag 4 so that air can smoothly enter the mouth portion 25 of the bag 4 as a trigger for the upper and lower film sheets of the mouth portion 25 of the bag 4 led into the interval between the conveyor belts 20 and 21 to be drawn and separated from each other. Hence, before the mouth portion 25 of the bag 4 enters the interval between the conveyor belts 20 and 21 and after the mouth opening of the bag 4 is completed, the air blowing port of the sirocco fan 13 is shut off by the air shutter 15 so that the mouth portion 25 of the bag 4 is prevented from being deformed by the air blowing from the sirocco fan 13 or the mouth that is already opened is prevented from being closed.

Before the mouth portion 25 of the bag 4 on the belt conveyors 10, 11 conveyed in the direction of arrow 5 by the blade conveyor 6 comes to the position where the conveyor belts 20, 21 are arranged, it is preferable that an appropriate blower 8 for blowing air from above toward the mouth portion 25 of the bag 4 is provided so that the mouth portion 25 of the bag 4 is shaped flat on the belt conveyors 10, 11. By so doing, the mouth portion 25 entering between the conveyor belts 20 and 21 can be smoothly opened.

When the bag 4 having the mouth portion 25 opened comes to the position of arrow C in FIG. 1 where the mouth spreader bars 30 are arranged, the mouth spreader bars 30 having their distal ends narrowed, as shown in (c) of FIG. 6, are moved in the direction of arrow 35 to be inserted into the mouth portion 25 so opened. Then, the distal ends of the mouth spreader bars 30 are widened, as shown in (d) of FIG. 6, and thereby the mouth portion 25 of the bag 4 is laterally (horizontally) spread. Also, the air squeezer 41 is moved down and slightly pushes down the mouth portion 25 of the bag 4. Then, the mouth spreader bars 30 having the distal ends kept widened are retracted in the direction of arrow 36. Thereby, the bag 4 is pulled to the direction of the mouth spreader bars 30. At the same time, the air cylinder 48 is elongated and the pusher bar 49 pushes out the bottom of the bag 4 in the direction of arrow 42 (FIG. 5). By this action, the bag 4 having the sliced bread is moved to the mouth portion 25 so that air existing in the non-filled space 43 formed in front of the sliced bread filled in the bag 4 is squeezed between the air squeezer 41 and belt conveyor 10 to be discharged outside.

If the air squeezing only by the air squeezer 41 and pusher bar 49 of the air existing in the non-filled space 43 formed in front of the sliced bread filled in the bag 4 is not sufficient, as shown in (c) of FIG. 7, a suction pipe 37 is provided to be inserted into, and drawn out of, the mouth portion 25 of the bag 4 together with the mouth spreader bars 30 and the air existing in the non-filled space 43, etc. in the bag 4 can be discharged outside by this suction pipe 37.

In this way, the mouth portion 25 of the bag 4 spread flat on the belt conveyors 10, 11 so that the lower surface of the bag 4 sticks to the belt conveyors 10, 11 are pinched and sealed between the sealer 50 and sealer receiver 52 so that the sealed portion 60 is formed air tight. The bag 4 together with the sliced bread so sealed is sent to the binder 70 and the portion on the mouth side of the bag 4 is appropriately folded and bound.

Sealing of the bag 4 by the sealer 50 is preferable to be so made that while the sealing of the mouth portion 25 of the bag 4 is achieved sufficiently tight by adhesion, when a consumer wants to take out the packaged sliced bread, the sealing can be easily peeled off by hand. One example of such sealing is disclosed by the Japanese laid-open patent application 2001-247101 filed by the same applicant here, in which such an adhesive layer is employed as effects an adhesion by heating to a temperature not higher than a seal temperature of a film constituting the bag 4 and this adhesive layer is previously applied to the sealed portion so that the mouth portion is tentatively weakly sealed.

Embodiment 2

Next, a packaging method according to Embodiment 2 of the present invention will be described with reference to FIG. 9. The present Embodiment 2 is an example where the construction of the conveyor belts through which the suction force acts on the upper and lower sides of the mouth portion of the bag is modified.

FIG. 9 is a side view of upper and lower conveyor belts 120, 121 used in place of the upper and lower conveyor belts 20, 21 of the Embodiment 1 shown in FIG. 4 as well as shown by broken lines of FIG. 1. As somewhat exaggeratedly shown in FIG. 9 being a view shown in the direction of arrow C in FIG. 1, with respect to the two conveyor belts 120, 121, the conveyor belt 120 is obliquely arranged relative to the conveyor belt 121 so that an interval between the two conveyor belts 120 and 121 is gradually increased toward a running direction of the bag 4.

Each of the conveyor belts 120, 121 is constructed by a porous belt having a multiplicity of small holes of appropriate sizes to be permeable.

Within loops formed by the conveyor belts 120, 121, there are provided vacuum chambers 123, 124, respectively, and suction forces from the vacuum chambers 123, 124 act on the mouth portion of the bag 4 through the conveyor belts 120, 121 constructed by the porous belt. This functions to suck upper and lower two plastic sheets constituting the mouth portion of the bag 4 so as to separate them from each other.

As described with respect to the Embodiment 1, at the position where the conveyor belts 120, 121 are arranged, the same sirocco fan 13 as described with respect to FIG. 1 is provided. When the mouth portion of the bag 4 is led into the interval between the conveyor belts 120 and 121, air is blown toward the mouth of the bag 4 from the sirocco fan 13. Thereby, a small opening of the mouth of the bag 4 is formed as a trigger of the bag opening and when the suction forces from the vacuum chambers 123, 124 act through the conveyor belts 120, 121, air easily enters the bag 4 so that the bag opening can be easily and securely carried out.

As the air from the sirocco fan 13 is needed only for forming the small opening of the mouth of the bag 4 as the trigger of the bag opening, as in the case of the Embodiment 1, the air blowing toward the mouth of the bag 4 that is being conveyed is also needed only for a short time while the bag 4 is nearby passing. For this purpose, the air cylinder 14 moves the air shutter 15 so that the air from the sirocco fan 13 is blown or the air blowing is shut off.

Then, as mentioned above, the mouth spreader bars 30 are inserted into the mouth portion of the bag 4 so opened and by the interval between the distal ends of the mouth spreader bars 30 being laterally widened, the mouth portion of the bag 4 is spread flat.

While the present invention has been concretely described based on the embodiments as illustrated, as a matter of course, the present invention is not limited to the embodiments but may be added with various modifications in the concrete structure and construction without departing from the scope of the claims of the present invention.

For example, in the embodiments, while the two conveyor belts 20, 21 or 120, 121 having the air suction holes are used for causing the suction forces to act on the mouth portion of the bag 4, not being limited to such construction, other means of appropriate constructions may be employed if they can cause a suction force to act on both sides, opposed to each other, of the mouth portion of the bag so as to open the mouth portion of the bag. As one example thereof, in place of the conveyor belts 20, 21 or 120, 121, a plurality of conveyor belts, having no air suction hole, arranged with intervals maintained in the lateral direction between each of the conveyor belts may be employed so that suction forces from vacuum chambers act on the mouth portion of the bag 4 through the intervals between each of the conveyor belts.

Also, in the embodiments, while the construction is made such that the air shutter 15 is moved to intermittently effect the air blowing toward the mouth of the bag while the suction force is being caused to act on the mouth portion of the bag, the construction may be simplified such that the air blowing force is appropriately adjusted to thereby continuously blow the air.

Further, in the embodiments, as the mouth spreader bars 30, while the structure that the interval between the bar distal ends is pivotally widened or narrowed is employed, in place thereof, mouth spreader bars of such structure that an interval between the bars arranged in parallel to each other is widened and narrowed may be employed.

Furthermore, in the embodiments, while the air discharging operation before the sealing of the bag 4 having the sliced bread is carried out by the air squeezer 41 moving up and down so that the air in the non-filled space 43 in the bag 4 is squeezed to be discharged outside as well as by the bag 4 being moved, according to the kind of packaged articles, the air discharge is not essential and may be omitted according to the case.

Also, in the embodiments, while one sirocco fan 13 is provided for opening the mouth of the bag 4, a plurality of such sirocco fans may be provided. In this case, air blowing and shutting of air blowing may be sequentially done corresponding to the bag 4 being conveyed.

Also, in the embodiments, while the belt conveyors 10, 11 conveying the mouth portion of the bag 4 having the sliced bread are made of an adhesive material relative to the plastic-made bag 4 so that holding of the mouth portion of the bag spread flat thereon is securely carried out, a carrier belt as used for the present invention is not limited thereto but may be made of generally obtainable materials of belt conveyor. Or in order for the mouth portion of the bag to be securely held, as the carrier belt, such a belt as has openings through which air is sucked out may be used. Or, as shown in FIG. 10, there is employed a vacuum chamber 17 having suction holes 16 and the belt conveyors 10, 11 or chains are arranged to run on the vacuum chamber 17. Thereby, suction force acts on the mouth portion of the bag through the suction holes 16 and through between the carrier belts and the mouth portion of the bag can be conveyed being securely held. In case the belt conveyor 10 and/or 11 is constructed by such a porous belt, the function of the conveyor belt 21, 121 and vacuum chamber 24, 124 used in the above-mentioned Embodiments can be taken over by the belt conveyor 10 and/or 11 and vacuum chamber 17, respectively, and the conveyor belt 21, 121 and vacuum chamber 24, 124 can be omitted.

Also, in the embodiments, while the construction having the mouth spreader bars 30 arranged at a static position has been described, the mouth spreader bars 30 may be constructed movable such that when they are moved to the sirocco fan 13 as shown by arrow 26 in FIG. 1, they are quickly inserted into the mouth portion of the bag 4 as soon as the mouth of the bag 4 is opened and then when they are returned to the position of arrow C as shown by arrow 27, they do the action to spread the mouth portion of the bag 4 flat. Thereby, the length of arrangement of the conveyor belts 20, 21 or 120, 121 for maintaining the mouth portion of the bag 4 opened can be shortened.

Furthermore, like the mouth spreader bars 30, the air cylinder 48 and pusher bar 49 may also be constructed to be moved together with the mouth spreader bars 30 in the directions shown by arrows 26, 27 so that squeezing of the air remaining in the bag 4 can be quickly done as soon as the mouth opening of the bag 4 is carried out. Thereby, the length of arrangement of the conveyor belts 20, 21 or 120, 121 can be further shortened.

As concretely described above, according to the bag packaging method of the present invention, while the suction force is caused to act on both sides, opposed to each other, of the mouth portion of the bag filled with articles, air is blown toward the mouth of the bag to thereby securely open the mouth portion of the bag. Then, two mouth spreader bars 30 are inserted into the mouth portion of the bag so opened and the interval between distal ends of the mouth spreader bars 30 is laterally (horizontally) widened. Thus, the mouth portion of the bag filled with articles is quickly spread flat and the mouth portion of the bag so spread flat is pinched and sealed by the sealer. Hence, even if the bag is made of a very thin and weak plastic film, the sealing can be done without generation of creases. 

1. A bag packaging method comprising the steps of: while causing a suction force to act on both sides, opposed to each other, of a mouth portion of a bag filled with articles, opening the mouth portion of said bag by blowing air toward a mouth of said bag, inserting two mouth spreader bars having an interval between their distal ends narrowed into said bag so opened, causing said mouth spreader bars to have the interval laterally widened to thereby spread the mouth portion of said bag flat, and causing a sealer to pinch and seal the mouth portion of said bag so laterally spread.
 2. A bag packaging method as claimed in claim 1, wherein said step of causing the suction force to act on the both sides of said bag is carried out by leading the mouth portion of said bag between upper and lower two conveyor belts, each comprising an air suction means, arranged to run in a running direction of said bag with an interval maintained between said two conveyor belts.
 3. A bag packaging method as claimed in claim 2, wherein said two conveyor belts are arranged such that the interval between said two conveyor belts is gradually increased toward the running direction of said bag.
 4. A bag packaging method as claimed in claim 1, comprising the steps of: causing an air squeezer to push the mouth portion of said bag so spread flat by said mouth spreader bars, moving said bag relative to said air squeezer to thereby cause said air squeezer to squeeze air existing between the mouth of said bag and the articles filled in said bag to be discharged outside, and then carrying out the sealing of the mouth portion of said bag.
 5. A bag packaging method as claimed in claim 4, comprising the step of: carrying out the movement of said bag relative to said air squeezer by retraction of said mouth spreader bars as well as by pushing out a bottom portion of said bag to thereby carry out the discharge of said air.
 6. A bag packaging method as claimed in claim 1, comprising the steps of: inserting an air suction pipe together with said two mouth spreader bars into said bag having the mouth so opened, causing said air suction pipe to suck out air in said bag having the mouth portion so spread flat by said mouth spreader bars to be discharged outside, and then carrying out the sealing of the mouth portion of said bag having the air so discharged outside.
 7. A bag packaging method as claimed in claim 2, comprising the steps of: causing an air squeezer to push the mouth portion of said bag so spread flat by said mouth spreader bars, moving said bag relative to said air squeezer to thereby cause said air squeezer to squeeze air existing between the mouth of said bag and the articles filled in said bag to be discharged outside, and then carrying out the sealing of the mouth portion of said bag.
 8. A bag packaging method as claimed in claim 7, comprising the step of: carrying out the movement of said bag relative to said air squeezer by retraction of said mouth spreader bars as well as by pushing out a bottom portion of said bag to thereby carry out the discharge of said air.
 9. A bag packaging method as claimed in claim 2, comprising the steps of: inserting an air suction pipe together with said two mouth spreader bars into said bag having the mouth so opened, causing said air suction pipe to suck out air in said bag having the mouth portion so spread flat by said mouth spreader bars to be discharged outside, and then carrying out the sealing of the mouth portion of said bag having the air so discharged outside. 